You can link one system to another to gain bonus attributes. For example we could link your salvage array to a cannon array and gain a higher rate of fire.
Heres how:
We start by placing our primary system controller (Salvage Computer) and it's corresponding module (Salvage cannon).
The orange and purple wobbling boxes show what is linked together. Orange shows the controller, purple shows the module.
This happens automatically, but you can manually select and link by using C to select / deselect and V to link.
Repeat the same process for our secondary system. This is what will be linked, or "Slaved" to the "Master".
Same order again, controller placed first, modules second. Pressing C on the controller ends the select / link mode.
Now for the last step. This is what gives our bonus. We simply select our primary controller (salvage computer) with C.
This brings up our orange wobble box again, and shows the attached modules in purple.
Now press V on our targeted secondary controller (cannon computer).
It shows the "Slaved" system in blue. To exit the selection mode, press C again on the salvage computer.
To check your newly modified system, have a look in the weapons tab (T).
To explore what link ratios and combinations achieve, take a look at this graph.
http://starmadedock.net/threads/a-simple-graph-for-weapon-linking.3751/
(Another useful tip, you can select stacks of modules at a time to be linked by pressing shift V on a targeted group of them.)
Hopefully this makes sense! If not, just say, i'll get someone more competent to explain it :D